As a technology for achieving acceleration according to a driver's intention of accelerating, Patent Literature 1 shows description of achieving a satisfied acceleration in the following manner. That is, a driver performs switching operation to change the throttle opening degree characteristic, which is the relationship between the operation amount of an accelerator pedal and the throttle opening degree of an internal combustion engine, so that the throttle opening degree of the internal combustion engine becomes large even with a small operation amount of an accelerator pedal.